/*! \page InputDoc Input Overview


<H1>Input Files</H1>
Basic rules: <br>
<ul>
<li>Comments are '#', and extend until the end of the line.</li>

<li>Whitespace is ignored.  A space is the same as a tab is the same as a newline.  The only exception is the comment,
which is terminated by a newline. </li>

<li>Input is keyword-based, with the keywords case-insensitive.  In this manual, keywords will always be listed in
 all caps in a hope of clarity.
 There are three basic types of keywords: flags, single-value and sections.  Flags simply turn a feature on or off.  They're
 only a keyword with no options following them, for example CDMC, which enables continuous DMC.  Single-value 
 keywords have exactly one
 value following them, for example NCONFIG 1000, which calls for 1000 configurations.  Section keywords are followed
 by an open brace, a whitespace-delimited list of values, and a close brace, for example: STATES { 1 2 3 4 }.</li>

<li>Keywords are (almost) order-independent; in the case of a keyword appearing several times when only one is needed,
    the first instance will be selected.  There are a few exceptions to the order-independent rule:
  <ul>
    <li> Several METHOD sections will be executed in the order they appear in the file.  For example, 
	 one could list a VMC method, then OPTIMIZE, then VMC again to do a complete wave function optimization. </li>
    <li> The type of a section must be the first word in the section.  For example, to run a VMC calculation, one
         must enter METHOD { VMC  (other options) } </li>
  </ul>
</li>

<li>The architecture is pluggable.  There are several places that contain a Basis_function object--a molecular orbital
set, Jastrow factor, or a pseudopotential.  These are all interchangeable.  Molecular orbitals can be plugged into
either a slater determinant or enclosed in a PLOT method. </li>

</ul>
*/
